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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

MAIASPINA GLACIER                                       57
fall from its front; and, moreover, there were places where it had encroached on the fringing forest; but there was no basis upon which we could determine the amount of forward motion. It is probable, however, that the amount of advance and thickening was not nearly so great here as in other glaciers, for there was a broad area of piedmont ice in which the energy of the forward thrust could be dissipated, that it is hardly to be expected that extensive thickening and advance could also be caused. It is remarkable that so vast an area of piedmont ice should have been affected (approximately 300 square miles) and this could only have resulted from a thrust of great vigor from the Marvine Glacier on its emergence from the mountain valley.
Again Inactive in 1909. In the report on the expeditions of 1905 and 1906,1 it was predicted that the new cycle of advance of Marvine lobe would probably end in a treeless and moraine-free glacier margin after another season's melting had destroyed the forest and removed much of the moraine. Speaking of the advancing glaciers in general it was inferred that in each case stagnation would soon follow the dying out of the wave of advance, after which ablation moraine would again cover the glacier margins. The latter prediction was fully borne out by our studies of 1909, but the former was not.
By the time we approached the margin of the Malaspina Glacier in 1909 we had already satisfied ourselves as to the main elements in the problems of the advancing glaciers, and felt little need of a comparative study of the Malaspina margin, which we had at first thought of undertaking. To have done so meant the entire abandonment of our plan of visiting the Prince William Sound region, for the difficulties of travel up Kwik valley are so great that several weeks would be required, and the route through Floral Pass was closed to us by the recent advance and resulting broken surface of Lucia Glacier. We, therefore, undertook nothing further than an examination of the Marvine lobe from elevated points at a distance, from which, however, we could clearly see its condition even with the naked eye, and satisfied ourselves that it showed no new features of importance that were not exhibited by other advancing glaciers of the 1906 group. In 1910 the ice jam in Yakutat Bay made it impossible to land on the west side of the bay and examination of Marvine lobe with field glasses added no significant facts to those observed the previous year. In 1911 Marvine Glacier was once more so little crevassed that it wa.s easily crossed in its mountain valley by a Boundary Survey party. In September, 1918, the Marvine lobe of Malaspina Glacier was examined from a distance with field glasses by the junior author. It seemed to be entirely stagnant and inactive, the margin being again covered with ablation moraine.
All these observations clearly indicate that the advance of 1906 was short-lived, and that by July, 1909, it had completely ceased. Moreover, ablation had so healed the broken surface and margin that we were convinced that the advance ended soon after August, 1906. In the clear ice area of the Marvine lobe back of the margin, the ice surface looked much as it did in 1905; similar swirls of moraine were seen and the surface looked quite smooth. Doubtless a nearer view would have shown that the surface was far rougher than in 1890 and 1897 but it was certainly much less irregular than in 1906, and it appeared probable that one could travel over the glacier surface with no great difficulty.
The eastern margin of the Malaspina was also noticeably healed, as compared with the 1906 condition, though still rough, broken and steep. The jagged marginal cliff had disappeared, though steep ice cliffs still appeared in places, and while much of the
> Tarr, B. S., Professional Paper 64, IT. 8. Geol. Survey, 1909, pp. 87 and 94.